Structure of goa circuit

ABSTRACT

The invention provides a structure of GOA circuit, which is manufactured on both sides of the ultra-thin flexible substrate with holes, wherein the wires pass through the holes to connect the TFTs in the GOA circuit on the front side to the TFTs in the GOA circuit on the back side to reduce the area occupied by GOA circuit. As such, the circuit area utilization is improved so that the same size of substrate area can carry almost twice the circuit structure to reduce the border width of the non-active area to achieve borderless or ultra-narrow border display panel with high resolution.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of display techniques, and inparticular to a structure of gate on array (GOA) circuit.

2. The Related Arts

The liquid crystal display (LCD) provides many advantages, such asthinness, low power-consumption and no radiation, and is widely used in,such as, LCD televisions, mobile phones, personal digital assistants(PDAs), digital cameras, computer screens, laptop screens, and so on.The LCD also dominates the field of panel displays.

Most of the LCDs on the current market are of backlight type, whichcomprises an LCD panel and a backlight module. The operation theorybehind LCD is to inject the liquid crystal (LC) molecules between a thinfilm transistor (TFT) array substrate and a color filter (CF) substrate,and applies a driving voltage between the two substrates to control therotation direction of the LC molecules to refract the light from thebacklight module to generate the display on the screen.

The active matrix liquid crystal display (AMLCD) is the most commonlyused liquid crystal display, which comprises a plurality of pixels, eachpixel is controlled by a TFT, the gate of the TFT is connected to a scanline in a horizontal direction, the drain is connected to a data line ina vertical direction, and the source is connected to a correspondingpixel electrode. When a sufficient positive voltage is applied to a scanline in the horizontal direction, all of the TFTs connected to the scanline are turned on, the data signal voltage loaded on the data line iswritten into the pixel electrode to control the transmittance ofdifferent liquid crystals to achieve the effect of color control.

The driving of the horizontal scan line (i.e., gate driving) of theAMLCD horizontal is initially executed by an external integrated circuit(IC). The external IC can control the charge and discharge of thehorizontal scan line in each stage progressively. The gate driver onarray (GOA) technology, i.e., the array substrate column drivingtechnology, can use the array process of the LCD panel to manufacturethe driver circuit of the horizontal scan lines on the substrate at areasurrounding the active area to replace the external IC for driving thehorizontal scan lines. The GOA technology can reduce the bonding processfor external IC and has the opportunity to enhance yield rate and reduceproduction cost, as well as make the LCD panel more suitable for theproduction of narrow border display products.

As the display technology progresses, the resolution of the display isalso higher and higher. For the displays of the same size, the higherthe resolution of the display, the high the number of the stages of GOAcircuit is required, and more routing area is occupied, which needswider display panel border, and is not suitable for the realization ofultra-narrow border or borderless display panel. As a result, the GOAcircuit lost the advantages in the production of narrow border displayproduct.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a structure of GOAcircuit, able to reduce the routing area required by the GOA circuit toreduce the width of non-active area of LCD to achieve ultra-narrowborder borderless display.

To achieve the above object, the present invention provides a structureof GOA circuit, which comprises: a flexible substrate, a first thin filmtransistor (TFT) layer disposed on the front side of the flexiblesubstrate, a second TFT disposed on the back side of the flexiblesubstrate, and a plurality of wires passing through a plurality of holeson the flexible substrate to electrically connected the first TFT layerand the second TFT layer respectively.

According to a preferred embodiment of the present invention, thematerial of the flexible substrate is polyimide, polyethyleneterephthalate, cycloolefin copolymer, or polyether resin.

According to a preferred embodiment of the present invention, thethickness of the flexible substrate is 10-300 μm.

According to a preferred embodiment of the present invention, both thefirst TFT layer and the second TFT layer comprise at least a TFT, andeach TFT comprises a gate disposed on the flexible substrate, a gateinsulation layer covering the gate, a semiconductor layer disposed onthe gate insulation layer on the gate, and a source and a drain disposedon the gate insulation layer and contacting respectively the two ends ofthe semiconductor layer.

According to a preferred embodiment of the present invention, theplurality of holes and the plurality of wires are in a one-to-onecorrespondence, with each hole disposed with a wire.

According to a preferred embodiment of the present invention, each holeis disposed with at least two wires, and each wire in the same hole isseparated from the others by an insulation layer.

According to a preferred embodiment of the present invention, the secondTFT layer and the wires disposed on the back side of the flexiblesubstrate are covered with a protective layer.

According to a preferred embodiment of the present invention, thematerial for the protective layer is silicon oxide.

According to a preferred embodiment of the present invention, theplurality of holes is formed by a laser drilling process or a chemicaletching process.

According to a preferred embodiment of the present invention, the wiresare made of copper or grapheme.

Another embodiment of the present invention provides a structure of GOAcircuit, which comprises: a flexible substrate, a first thin filmtransistor (TFT) layer disposed on the front side of the flexiblesubstrate, a second TFT disposed on the back side of the flexiblesubstrate, and a plurality of wires passing through a plurality of holeson the flexible substrate to electrically connected the first TFT layerand the second TFT layer respectively;

wherein the material of the flexible substrate being polyimide,polyethylene terephthalate, cycloolefin copolymer, or polyether resin;

wherein the thickness of the flexible substrate is 10-300 μm.

Compared to the known techniques, the present invention provides thefollowing advantages. The present invention provides a structure of GOAcircuit, which is manufactured on both sides of the ultra-thin flexiblesubstrate with holes, wherein the wires pass through the holes toconnect the TFTs in the GOA circuit on the front side to the TFTs in theGOA circuit on the back side to reduce the area occupied by GOA circuit.As such, the circuit area utilization is improved so that the same sizeof substrate area can carry almost twice the circuit structure to reducethe border width of the non-active area to achieve borderless orultra-narrow border display panel with high resolution.

BRIEF DESCRIPTION OF THE DRAWINGS

To make the technical solution of the embodiments according to thepresent invention, a brief description of the drawings that arenecessary for the illustration of the embodiments will be given asfollows. Apparently, the drawings described below show only exampleembodiments of the present invention and for those having ordinaryskills in the art, other drawings may be easily obtained from thesedrawings without paying any creative effort. In the drawings:

FIG. 1 is a front view showing a structure of GOA circuit provided bythe first embodiment of the present invention;

FIG. 2 is a back view showing a structure of GOA circuit provided by thefirst embodiment of the present invention;

FIG. 3 is a cross-sectional view showing a structure of GOA circuitprovided by the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further explain the technique means and effect of the presentinvention, the following uses preferred embodiments and drawings fordetailed description.

Referring to FIGS. 1-3, the present invention provides a structure ofGOA circuit, which comprises: a flexible substrate 1, a first thin filmtransistor (TFT) layer 2 disposed on the front side of the flexiblesubstrate 1, a second TFT 3 disposed on the back side of the flexiblesubstrate 1, and a plurality of wires 5 passing through a plurality ofholes 4 on the flexible substrate 1 to electrically connected the firstTFT layer 2 and the second TFT layer 3 respectively.

It should be noted that because a plurality of signal inputs is requiredfor TFT connections, the connections between the first TFT layer 2 andthe second TFT layer 3 need a plurality of wires 5 for transportingdifferent signals. The wires 5 transporting different signals can be, asshown in FIG. 1 and FIG. 2, a plurality of wires separated by insulationlayer in the same hole 4 to transport different signals (i.e., amulti-layer metal structure in the hole 4), or as shown in FIG. 3, eachhole corresponds to a wire 5 only, and the wires 5 for different signalsare disposed separately (i.e., each hole 4 only comprises a single metallayer structure.)

Specifically, referring to FIG. 1 and FIG. 2, the first embodiment ofthe present invention adopts the approach that a plurality of wiresseparated by insulation layer in the same hole 4, which is a typical 4Tstructure GOA circuit, comprising: a first TFT T1, a second TFT T2, athird TFT T3 and a fourth TFT T4, wherein the first TFT T1 and thesecond TFT T2 are located at the first TFT layer 2 formed on the frontside of the flexible substrate 1, and the third TFT T3 and the fourthTFT T4 are located at the second TFT layer 3 formed on the back side ofthe flexible substrate 1. The flexible substrate 1 is disposed with ahole 4, and the hole 4 is disposed with two wires 5, with one of thewires 5 passing through the hole 4 to connect the drain of the first TFTt1 to the source of the fourth TFT T4, and the other also passingthrough the hole 4 to connect the drain of the second TFT T2 to thesource of the third TFT T3 and the gate of the fourth TFT T4. The twowires 5 are separated by an insulation layer (not shown).

Specifically, referring to FIG. 3, the second embodiment of the presentinvention adopts the approach that each hole 4 is disposed with a singlewire 5. The second embodiment shows a preferred TFT structure of thepresent invention, comprising: a gate 21 disposed on the flexiblesubstrate 1, a gate insulation layer 22 covering the gate 21, asemiconductor layer 23 disposed on the gate insulation layer 22 on thegate 21, and a source 24 and a drain 25 disposed on the gate insulationlayer 22 and contacting respectively the two ends of the semiconductorlayer 23. As shown in FIG. 3, the wire 5 for connecting the gates 21 ofthe two TFTs on the front side and back side of the flexible substrate1, and the wire 5 for connecting the drain 25 of the two TFTs on thefront side and back side of the flexible substrate 1 are located indifferent holes 4.

It should be noted that the TFT structure shown in the second embodimentcan also be applied to the first embodiment. The present invention canalso use other TFT structure, without affecting the realization of thepresent invention.

Furthermore, the material of the flexible substrate is polyimide,polyethylene terephthalate, cycloolefin copolymer, or polyether resin;and the thickness of the flexible substrate is 10-300 μm. Because thepresent invention adopts double-sided circuit structure and the holes 4are formed on the flexible substrate 1 for the wires 5 to pass throughto connect circuits on both sides. Therefore, the present inventionadopts the flexible substrate 1, which is much thinner than theconventional glass substrate, to ensure the required number of holes 4to be formed during the flexible substrate manufacturing process, aswell as the conductivity of the wires 5. The plurality of holes 4 isformed by a laser drilling process or a chemical etching process; andthe wires 5 are made of copper or grapheme, or other metal orsemiconductors with good conductivity.

In addition, to protect the circuit on the back side of the flexiblesubstrate 1, the second TFT layer 3 and the wires 5 disposed on the backside of the flexible substrate 1 are covered with a protective layer,wherein the material for the protective layer is silicon oxide (SiOx),or other oxide.

In summary, the present invention provides a structure of GOA circuit,which is manufactured on both sides of the ultra-thin flexible substratewith holes, wherein the wires pass through the holes to connect the TFTsin the GOA circuit on the front side to the TFTs in the GOA circuit onthe back side to reduce the area occupied by GOA circuit. As such, thecircuit area utilization is improved so that the same size of substratearea can carry almost twice the circuit structure to reduce the borderwidth of the non-active area to achieve borderless or ultra-narrowborder display panel with high resolution.

It should be noted that in the present disclosure the terms, such as,first, second are only for distinguishing an entity or operation fromanother entity or operation, and does not imply any specific relation ororder between the entities or operations. Also, the terms “comprises”,“include”, and other similar variations, do not exclude the inclusion ofother non-listed elements. Without further restrictions, the expression“comprises a . . . ” does not exclude other identical elements frompresence besides the listed elements.

Embodiments of the present invention have been described, but notintending to impose any unduly constraint to the appended claims. Anymodification of equivalent structure or equivalent process madeaccording to the disclosure and drawings of the present invention, orany application thereof, directly or indirectly, to other related fieldsof technique, is considered encompassed in the scope of protectiondefined by the claims of the present invention.

What is claimed is:
 1. A structure of GOA (gate driver on array)circuit, which comprises: a flexible substrate, a first thin filmtransistor (TFT) layer disposed on the front side of the flexiblesubstrate, a second TFT disposed on the back side of the flexiblesubstrate, and a plurality of wires passing through a plurality of holeson the flexible substrate to electrically connected the first TFT layerand the second TFT layer respectively.
 2. The structure of GOA circuitas claimed in claim 1, wherein the material of the flexible substrate ispolyimide, polyethylene terephthalate, cycloolefin copolymer, orpolyether resin.
 3. The structure of GOA circuit as claimed in claim 1,wherein the thickness of the flexible substrate is 10-300 μm.
 4. Thestructure of GOA circuit as claimed in claim 1, wherein both the firstTFT layer and the second TFT layer comprise at least a TFT, and each TFTcomprises a gate disposed on the flexible substrate, a gate insulationlayer covering the gate, a semiconductor layer disposed on the gateinsulation layer on the gate, and a source and a drain disposed on thegate insulation layer and contacting respectively the two ends of thesemiconductor layer.
 5. The structure of GOA circuit as claimed in claim1, wherein the plurality of holes and the plurality of wires are in aone-to-one correspondence, with each hole disposed with a wire.
 6. Thestructure of GOA circuit as claimed in claim 1, wherein each hole isdisposed with at least two wires, and each wire in the same hole isseparated from the others by an insulation layer.
 7. The structure ofGOA circuit as claimed in claim 1, wherein the second TFT layer and thewires disposed on the back side of the flexible substrate are coveredwith a protective layer.
 8. The structure of GOA circuit as claimed inclaim 7, wherein the material for the protective layer is silicon oxide.9. The structure of GOA circuit as claimed in claim 1, wherein theplurality of holes is formed by a laser drilling process or a chemicaletching process.
 10. The structure of GOA circuit as claimed in claim 1,wherein the wires are made of copper or grapheme.
 11. A structure of GOA(gate driver on array) circuit, which comprises: a flexible substrate, afirst thin film transistor (TFT) layer disposed on the front side of theflexible substrate, a second TFT disposed on the back side of theflexible substrate, and a plurality of wires passing through a pluralityof holes on the flexible substrate to electrically connected the firstTFT layer and the second TFT layer respectively; wherein the material ofthe flexible substrate being polyimide, polyethylene terephthalate,cycloolefin copolymer, or polyether resin; wherein the thickness of theflexible substrate being 10-300 μm.
 12. The structure of GOA circuit asclaimed in claim 11, wherein both the first TFT layer and the second TFTlayer comprise at least a TFT, and each TFT comprises a gate disposed onthe flexible substrate, a gate insulation layer covering the gate, asemiconductor layer disposed on the gate insulation layer on the gate,and a source and a drain disposed on the gate insulation layer andcontacting respectively the two ends of the semiconductor layer.
 13. Thestructure of GOA circuit as claimed in claim 11, wherein the pluralityof holes and the plurality of wires are in a one-to-one correspondence,with each hole disposed with a wire.
 14. The structure of GOA circuit asclaimed in claim 11, wherein each hole is disposed with at least twowires, and each wire in the same hole is separated from the others by aninsulation layer.
 15. The structure of GOA circuit as claimed in claim11, wherein the second TFT layer and the wires disposed on the back sideof the flexible substrate are covered with a protective layer.
 16. Thestructure of GOA circuit as claimed in claim 15, wherein the materialfor the protective layer is silicon oxide.
 17. The structure of GOAcircuit as claimed in claim 11, wherein the plurality of holes is formedby a laser drilling process or a chemical etching process.
 18. Thestructure of GOA circuit as claimed in claim 11, wherein the wires aremade of copper or grapheme.